From: Adam Langley <agl@chromium.org>
Date: Mon, 8 Aug 2016 20:36:55 +0000 (-0700)
Subject: Fix test of first of 255 CBC padding bytes.
X-Git-Tag: OpenSSL_1_1_0~242
X-Git-Url: https://git.openssl.org/?p=openssl.git;a=commitdiff_plain;h=eea8723cd0d56398fc40d0337e9e730961c9c2fa

Fix test of first of 255 CBC padding bytes.

Thanks to Peter Gijsels for pointing out that if a CBC record has 255
bytes of padding, the first was not being checked.

(This is an import of change 80842bdb from BoringSSL.)

Reviewed-by: Emilia Käsper <emilia@openssl.org>
Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/1431)
---

diff --git a/ssl/record/ssl3_record.c b/ssl/record/ssl3_record.c
index ad240bc52d..49c6756376 100644
--- a/ssl/record/ssl3_record.c
+++ b/ssl/record/ssl3_record.c
@@ -1149,9 +1149,9 @@ int tls1_cbc_remove_padding(const SSL *s,
      * maximum amount of padding possible. (Again, the length of the record
      * is public information so we can use it.)
      */
-    to_check = 255;             /* maximum amount of padding. */
-    if (to_check > rec->length - 1)
-        to_check = rec->length - 1;
+    to_check = 256;            /* maximum amount of padding, inc length byte. */
+    if (to_check > rec->length)
+        to_check = rec->length;
 
     for (i = 0; i < to_check; i++) {
         unsigned char mask = constant_time_ge_8(padding_length, i);